Cog for coaster brake hub

Quoth Chuck Connell:

Quoted message said:

I need a part for my young daughter's bike. She has a one-speed coaster brake rear hub. It now
was an 18t sprocket on it. This is too high a gear, and she can not pedal up even a small hill. I
tried the bike myself and the gearing is extremely high for a kid. I would like to get some new
cogs for this hub, like a 20 and a 23, or something close to that. The cog has three little
splines on the inside diameter, to mate with the hub. Anybody got some of these??

These use the same sprockets as most internal-gear hubs. We have them up to 22 teeth. We usually
also have 24s, but those have been back-ordered for a while.

Go to sheldonbrown.comsturmey.htmlOpen ↗ and scroll down to the sprocket section.

If you go much larger, you may need a new chain (the axle moves forward
1/8" for each additional tooth.

Another option would be to replace the chainwheel in front with a smaller one. If the bike has
one-piece cranks, this is cheap and easy.

See: sheldonbrown.comopc.htmlOpen ↗

Sheldon "Little Stuff" Brown +---------------------------------------------------------------+
| The poet Henry O'Meara (1848-1904) was my great-grandfather | I've put his book "Ballads of
| America and Other Poems" | on the Web at: sheldonbrown.comomearaOpen ↗ |
+---------------------------------------------------------------+ Harris Cyclery, West Newton,
Massachusetts Phone 617-244-9772 FAX 617-244-1041 harriscyclery.comharriscyclery.comOpen ↗ Hard-to-find parts
shipped Worldwide captainbike.comcaptainbike.comOpen ↗ sheldonbrown.comsheldonbrown.comOpen ↗

Ancient coaster hubs have threaded cogs (the same 1 3/8" 24 tpi as the bottom bracket) and these are
somewhat difficult to obtain, but the splined ones are so common. You may got one of these in old
bike shops. The cogs made to the gear hubs SRAM or Sturmey-Archer, has the same spline pattern too.

all the best

Eduardo

"Chuck" <[email hidden]> escreveu na mensagem
"]news:[email hidden]...

Quoted message said:

Hi gang,

I know this is not very high-tech, but I need a part for my young daughter's bike. She has a
one-speed coaster brake rear hub. It now was an 18t sprocket on it. This is too high a gear, and
she can not pedal up even a small hill. I tried the bike myself and the gearing is extremely high
for a kid. I would like to get some new cogs for this hub, like a 20 and a 23, or something close
to that. The cog has three little splines on the inside diameter, to mate with the hub. Anybody
got some of these??

TIA, Chuck Connell [email hidden] 781-939-0505

---
Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (grisoft.comgrisoft.comOpen ↗).
Version: 6.0.529 / Virus Database: 324 - Release Date: 16/10/2003

[email hidden] (Chuck) wrote in message news:<[email hidden]>...

Quoted message said:

Hi gang,

I know this is not very high-tech, but I need a part for my young daughter's bike. She has a
one-speed coaster brake rear hub. It now was an 18t sprocket on it. This is too high a gear, and
she can not pedal up even a small hill. I tried the bike myself and the gearing is extremely high
for a kid. I would like to get some new cogs for this hub, like a 20 and a 23, or something close
to that. The cog has three little splines on the inside diameter, to mate with the hub. Anybody
got some of these??

TIA, Chuck Connell

Any decent LBS with a repair dept. probably has several of these sitting in a drawer in different
sizes collecting dust.

[email hidden] (Chuck) wrote in message news:<[email hidden]>...

Quoted message said:

Hi gang,

I know this is not very high-tech, but I need a part for my young daughter's bike. She has a
one-speed coaster brake rear hub. It now was an 18t sprocket on it. This is too high a gear, and
she can not pedal up even a small hill. I tried the bike myself and the gearing is extremely high
for a kid. I would like to get some new cogs for this hub, like a 20 and a 23, or something close
to that. The cog has three little splines on the inside diameter, to mate with the hub. Anybody
got some of these??

TIA, Chuck Connell [email hidden] 781-939-0505

Dear Chuck,

A once-common trick for off-road motorcycles needing lower gearing was to bolt a larger sprocket
onto the existing sprocket and lengthen the chain. These were usually thin chain-rings whose inner
edges just touched the existing sprocket's teeth.

If no proper rear cog can be found for your daughter's bike, it might be possible to drill holes in
the existing sprocket and bolt a larger sprocket onto its side. How tricky this would be depends on
the specifics of the bike.

Otherwise, you're hunting for a part without a name. Pictures, details, brand names, and so forth
would help here, but taking it to a local bike shop might be just as easy. If they have no parts,
they could still tell you more about it and then you could put the details up in another post.

Carl Fogel

Quoted message said:

Quoted message said:

I know this is not very high-tech, but I need a part for my young daughter's bike. She has a
one-speed coaster brake rear hub. It now was an 18t sprocket on it. This is too high a gear, and
she can not pedal up even a small hill. I tried the bike myself and the gearing is extremely high
for a kid. I would like to get some new cogs for this hub, like a 20 and a 23, or something close
to that. The cog has three little splines on the inside diameter, to mate with the hub. Anybody
got some of these??

A well-meaning poster suggested:

Quoted message said:

A once-common trick for off-road motorcycles needing lower gearing was to bolt a larger sprocket
onto the existing sprocket and lengthen the chain. These were usually thin chain-rings whose inner
edges just touched the existing sprocket's teeth.

If no proper rear cog can be found for your daughter's bike, it might be possible to drill holes
in the existing sprocket and bolt a larger sprocket onto its side. How tricky this would be
depends on the specifics of the bike.

Otherwise, you're hunting for a part without a name. Pictures, details, brand names, and so forth
would help here, but taking it to a local bike shop might be just as easy. If they have no parts,
they could still tell you more about it and then you could put the details up in another post.

I've already replied to the original posting, with the correct information, and I have an assortment
of suitable sprockets in stock.

I do feel the need to reply to this, however. This sort of mickeymouse rig might be OK for
motorcycles, or for a bicycle with a freewheel, but it could be very dangerous on a bicycle that
relies on a coaster brake to stop.

Because the load is bi-directional with a coaster brake, I'd worry about the bolts loosening up.

Also, the chainline would not be correct. Either of these flaws could lead to unexpected chain
derailment, and sudden, total loss of braking ability!

Sheldon "Never Trust A Coaster Brake Alone" Brown
+------------------------------------------------------------------+
| Honestly, I think we should just trust our president in every | decision that he makes and we
| should just support that. | -- Britney Spears, September 4, 2003 |
+------------------------------------------------------------------+ Harris Cyclery, West Newton,
Massachusetts Phone 617-244-9772 FAX 617-244-1041 harriscyclery.comharriscyclery.comOpen ↗ Hard-to-find parts
shipped Worldwide captainbike.comcaptainbike.comOpen ↗ sheldonbrown.comsheldonbrown.comOpen ↗

Chuck said:

I know this is not very high-tech, but I need a part for my young daughter's bike. She has a
one-speed coaster brake rear hub. It now was an 18t sprocket on it. This is too high a gear, and
she can not pedal up even a small hill. I tried the bike myself and the gearing is extremely high
for a kid. I would like to get some new cogs for this hub, like a 20 and a 23, or something close
to that. The cog has three little splines on the inside diameter, to mate with the hub. Anybody
got some of these??

Any LBS which services bicycles will have them. They are pretty much interchangeable among various
brands of coaster brake and two through seven speed hubs.

--
Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971

Quoted message said:

[email hidden] (Chuck) wrote in message
news:<[email hidden]>...

Quoted message said:

I know this is not very high-tech, but I need a part for my young daughter's bike. She has a
one-speed coaster brake rear hub. It now was an 18t sprocket on it. This is too high a gear, and
she can not pedal up even a small hill. I tried the bike myself and the gearing is extremely high
for a kid. I would like to get some new cogs for this hub, like a 20 and a 23, or something close
to that. The cog has three little splines on the inside diameter, to mate with the hub.

-snip-

Carl Fogel wrote: -snip-

Quoted message said:

If no proper rear cog can be found for your daughter's bike, it might be possible to drill holes
in the existing sprocket and bolt a larger sprocket onto its side. How tricky this would be
depends on the specifics of the bike.

Quoted message said:

Otherwise, you're hunting for a part without a name. Pictures, details, brand names, and so forth
would help here, but taking it to a local bike shop might be just as easy. If they have no parts,
they could still tell you more about it and then you could put the details up in another post.

Bicycle rear cogs are uniformly quite hard - try drilling one sometime - regardless of the
"specifics of the bike".

Part numbers? The 18t part is an HSL718. He wants a 21t HSL721 ( HSL720 is the circlip which holds
the sprocket and spacers in place.)

OK, now where are we? Oh yes in the bicycle business where hardly anyone knows part numbers.

He should go at any LBS which commonly services bicycles and ask for a three-splined cog for a
coaster brake hub of greater teeth than eigheeen.

Which is just what he asked for above. That should do it.

--
Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971

Quoted message said:

Sheldon "Never Trust A Coaster Brake Alone" Brown
+------------------------------------------------------------------+
| Honestly, I think we should just trust our president in every | decision that he makes and we
| should just support that. | -- Britney Spears, September 4, 2003 |
+------------------------------------------------------------------+

Isn't mocking Britney Spears kind of like fishing with dynamite? Still, was good for a chuckle.

Rob Strickland

Sheldon Brown <[email hidden]> wrote in message
news:<[email hidden]>...

Quoted message said:

Quoted message said:

Quoted message said:

I know this is not very high-tech, but I need a part for my young daughter's bike. She has a
one-speed coaster brake rear hub. It now was an 18t sprocket on it. This is too high a gear, and
she can not pedal up even a small hill. I tried the bike myself and the gearing is extremely
high for a kid. I would like to get some new cogs for this hub, like a 20 and a 23, or something
close to that. The cog has three little splines on the inside diameter, to mate with the hub.
Anybody got some of these??

A well-meaning poster suggested:

Quoted message said:

A once-common trick for off-road motorcycles needing lower gearing was to bolt a larger sprocket
onto the existing sprocket and lengthen the chain. These were usually thin chain-rings whose
inner edges just touched the existing sprocket's teeth.

If no proper rear cog can be found for your daughter's bike, it might be possible to drill holes
in the existing sprocket and bolt a larger sprocket onto its side. How tricky this would be
depends on the specifics of the bike.

Otherwise, you're hunting for a part without a name. Pictures, details, brand names, and so
forth would help here, but taking it to a local bike shop might be just as easy. If they have
no parts, they could still tell you more about it and then you could put the details up in
another post.

I've already replied to the original posting, with the correct information, and I have an
assortment of suitable sprockets in stock.

I do feel the need to reply to this, however. This sort of mickeymouse rig might be OK for
motorcycles, or for a bicycle with a freewheel, but it could be very dangerous on a bicycle that
relies on a coaster brake to stop.

Because the load is bi-directional with a coaster brake, I'd worry about the bolts loosening up.

Also, the chainline would not be correct. Either of these flaws could lead to unexpected chain
derailment, and sudden, total loss of braking ability!

Sheldon "Never Trust A Coaster Brake Alone" Brown
+------------------------------------------------------------------+
| Honestly, I think we should just trust our president in every | decision that he makes and we
| should just support that. | -- Britney Spears, September 4, 2003 |
+------------------------------------------------------------------+ Harris Cyclery, West Newton,
Massachusetts Phone 617-244-9772 FAX 617-244-1041 harriscyclery.comharriscyclery.comOpen ↗ Hard-to-find parts
shipped Worldwide captainbike.comcaptainbike.comOpen ↗ sheldonbrown.comsheldonbrown.comOpen ↗

Dear Sheldon,

As usual, I think that you're right--right down to the mickey-mouse motorcycle comment. Had I been
able to see your earlier post, my foot would be free from saliva, but my newsreader's connection to
the server seems to have an increasing lag--only the original post showed up, giving scope to my
bad advice.

When in doubt, I just trust your posts and harriscyclery web site in every decision--it's always
worked for me.

Carl "Britney" Fogel